Mobile phones, personal digital assistants, digital cameras, MP3 players, and other portable electronic devices utilize solid state lighting (SSL) devices, such as light emitting diodes (e.g., LEDs), for backlighting and other purposes. SSL devices are also used for signage, indoor lighting, outdoor lighting, and other types of general illumination. FIG. 1A is a cross-sectional view of an existing SSL device 10 at an intermediate stage of manufacturing. As shown in FIG. 1A, the SSL device 10 includes a growth substrate 20 and an LED structure 21 on the growth substrate 20. The growth substrate 20 includes a buffer material 22, and the LED structure has an N-type gallium nitride (N-type GaN) 24 grown on the buffer material 22, an active region 25 grown on the N-type GaN 24, and P-type gallium nitride (P-type GaN) 26 grown on the active region 25. The active region 25 can contain gallium nitride/indium gallium nitride (GaN/InGaN) multiple quantum wells (MQWs). The SSL device 10 can also include a conductive layer 27 deposited on the P-type GaN 26, a mirror 28 deposited on the conductive layer 27, and a diffusion barrier 29 or bonding material on the mirror 28. After forming the mirror 28 and/or the diffusion barrier 29, a support substrate 30 is bonded to the diffusion barrier 29.
FIG. 1B is a cross-sectional view of the SSL device 10 at a subsequent stage of manufacturing after the growth substrate 20 has been removed to expose the N-type GaN 24 and the device is inverted relative to FIG. 1A. A conductive material 32 is then deposited on the N-type GaN 24. The conductive material 32 can be a transparent conductive material, such as indium tin oxide (ITO). The conductive material 32 can define a first contact electrically coupled to the N-type GaN 24, and the conductive material 27, the mirror 28 and/or the diffusion barrier 29 can define a second contact electrically coupled to the P-type GaN 26.
FIG. 1C shows a packaged device 40 that includes a support 50 carrying the SSL device 10 and a converter material 60. The support 50 includes a first contact 51 electrically coupled to the first contact 32 (FIG. 1B) and a second contact 52 electrically coupled to the conductive material 27 (FIG. 1B). In operation, an electrical voltage is applied to the SSL device 10 via the contacts 51 and 52, and in response the LED structure 21 produces a first emission (e.g., a blue light) that stimulates the converter material 60 to emit a second emission (e.g., a yellow light). The combination of the first and second emissions appears white to human eyes if matched appropriately.
One drawback of manufacturing the SSL device 10 illustrated in FIG. 1B is that it is expensive to handle and package. Packaging and handling of the SSL device 10, in fact, are a substantial fraction of the total manufacturing cost.